I could use this too, I have a visual inventory system in a new project, as stuff gets chucked in the loot bag it piles up in a visually interesting way, the game features no other collision detection, so as the bag fills it causes slowdown.
The player does not need to interact with the contents in any way, and they are tracked in a seperate list. So if I could set all the objects that have fallen in and settled to non-moving then switch off physics for those further down the pile, it would reduce cpu load alot.
A similiar use is one many of you will have seen in action, where bodies that have recently become corpses and settled in their physics induced positionjs of occasionally amusing agony, they are then removed from the physical objects in play and just become decoration.
In another project I used a blood effect that could stick to walls, they have no need to remain physical objects after this has happened.